India, China, US and the EU are the largest emitters of carbon dioxide, the main contributor to global warming, with the countries together accounting for 58 per cent of emissions, scientists say.
The latest annual update of the Global Carbon Budget found that carbon dioxide emissions are set to rise again in 2014 - reaching a record high of 40 billion tonnes.
The update shows that CO2 emissions from burning fossil fuel are projected to rise by 2.5 per cent in 2014 - 65 per cent above 1990 levels, the reference year for the Kyoto Protocol.
India's CO2 emissions grew by 5.1 per cent in 2013, China's grew by 4.2 per cent and the US's grew by 2.9 per cent, according to the update.
China's CO2 emissions per person overtook emissions in the EU for the first time in 2013. China's emissions are now larger than the US and EU combined. 16 per cent of China's emissions are for goods and services which are exported elsewhere.
CO2 emissions are caused primarily by burning fossil fuels, as well as by cement production and deforestation, which accounts for 8 per cent of emissions.
The update shows that total future CO2 emissions cannot exceed 1,200 billion tonnes - for a likely 66 per cent chance of keeping average global warming under 2 degrees Celsius (since pre-industrial times).
At the current rate of CO2 emissions, this 1,200 billion tonne CO2 'quota' would be used up in around 30 years. This means that there is just one generation before the safeguards to a 2 degrees Celsius limit may be breached.
The international team of climate scientists say that to avoid this, more than half of all fossil fuel reserves may need to be left unexploited.
"The human influence on climate change is clear. We need substantial and sustained reductions in CO2 emissions from burning fossil fuels if we are to limit global climate change. We are nowhere near the commitments necessary to stay below 2 degrees Celsius of climate change, a level that will be already challenging to manage for most countries around the world, even for rich nations," Professor Corinne Le Quere, Director of the Tyndall Centre at the University of East Anglia (UEA), said.
"We have already used two-thirds of the total amount of carbon we can burn, in order to keep warming below the crucial 2 degrees Celsius level," Professor Pierre Friedlingstein, from the University of Exeter said.
"If we carry on at the current rate we will reach our limit in as little as 30 years' time - and that is without any continued growth in emission levels. The implication of no immediate action is worryingly clear - either we take a collective responsibility to make a difference, and soon, or it will be too late," Friedlingstein said.
